Not sure what exactly you're trying to achieve. Running multiple instances of the same Thunderbird version, each with a different profile, or Running multiple instances of different Thunderbird versions, each with a different profile? Please clarify.

Hi christ1,

Firstly, thank you for your super quick response.

To clarify and answer your question in one word: both ie. 1. multiple instances of the same Thunderbird version and; 2. multiple instances of different Thunderbird versions;

(as you've mentioned, in both scenarios, each instance with a different profile)

To be frank I'm not sure of the main benefits of the two scenarios. So I would be interested to know if there are solutions to both scenarios, with preference to the simplest solutions. I'm guessing with the latter, the drawback would be having multiple installations and therefore requiring additional installation space - are there any main/significant practical benefits of either scenarios?

I hope what I'm trying to achieve is now clear. If not please let me know. Happy to expand more or answer any more questions.

You can start a new instance using the -no-remote option. I don't think you need that when using different versions. As said before, for each instance make sure to start it with the desired profile using the -P option. Also see https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options

Thank you again for your reply christ1.

I'm aware of the remote option - fairly simple and easy - I remember using this on Windows. However, as far as I'm aware, there is no equivalent for Mac OS. Or atleast there is no equivalent without needing to use a bash-script and the associated risks as outlined previously.

On the link you posted (in the remote control section): https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options#Remote_Control

It mentions that: "This option is only available on X-Windows Unix platforms." - by Unix i'm guessing that would work on Mac? However under that section, it was referring only to Firefox no? Even still, this would require a bash-script to run from a single click, right?

I'm guessing if there's no equivalent solution then perhaps re-packaging the current Thunderbird under a new edition like Firefox Developer Edition or like Waterfox etc. might best. Is there a particular file that needs to be modified so that Mac recognises the modified installation as a separate app? Or should I post this as a new question?

I remember using this on Windows. However, as far as I'm aware, there is no equivalent for Mac OS.

Why do you think this wouldn't work on Mac OS? I'd expect this to work on each supported OS.

Or at least there is no equivalent without needing to use a bash-script and the associated risks as outlined previously.

I'm not sure why you think you'd need a shell script. I'm not on Mac OS, and I know very little about it. However, I'm fairly certain you can open a shell and start Thunderbird from the command line with these options. I'd expect there's also some sort of mechanism in Mac OS with some sort of graphical shortcut where you can set the CLI parameters. There certainly is on Linux.

On the link you posted (in the remote control section):

That's a different option unrelated to -no-remote we're talking about here.

"This option is only available on X-Windows Unix platforms."

That would include Mac OS.

However under that section, it was referring only to Firefox no?

It also applies to Thunderbird.

Thank you Christ1 for your quick reply.

Thank you for clarifying! I haven't tried it yet but I think I'm wrong. I think there is an equivalent for Mac OS. I think this would be the equivalent command line you were mentioning: open /Applications/Thunderbird.app --args -no-remote -P "notthedefaultprofile"

I'm not sure why you think you'd need a shell script. I'm not on Mac OS, and I know very little about it. However, I'm fairly certain you can open a shell and start Thunderbird from the command line with these options. I'd expect there's also some sort of mechanism in Mac OS with some sort of graphical shortcut where you can set the CLI parameters. There certainly is on Linux.

For anyone else reading this, shell means Terminal on Mac (had to google that one).

I have found the following link that shows how to convert a shell command into a clickable icon: https://www.macobserver.com/tmo/article/os-x-how-to-convert-a-terminal-command-into-a-double-clickable-desktop-file And perhaps this link is useful too: https://superuser.com/questions/16750/how-can-i-run-an-application-with-command-line-arguments-in-mac-os

Finally, please let me rephrase my question (perhaps I should post this as a new question): Is it possible to have two separate installations each with their own unique profiles (each stored in a different location) and where each can be run at the same time without any conflict of instance (or mix-up of profile)? I feel that this setup is safer as it reduces the chance of a mix-up/corruption of profiles.

Currently, I have ran into issues* when running two separate instances (each with their unique profile) of old and Quantum Firefox (I've installed both in different locations). I found it very useful to use both the old Firefox and the new Quantum Firefox at the same time. This is the command line I have been using: open /Applications/Firefoxquantum.app --args -P Firefoxquantumprofile

`*Sometimes clicking when when clicking on an out-of-browser link, there seems to be a mix-up of profiles and consequently sometimes corrupts the old firefox profile - I lost some add-ons, add-on settings, bookmarks and some other damage too. As I'm not an expert in these things, it's possible that the script that I used is faulty. However, I've also noticed that others have ran into issues (see reddit link in original post).

open /Applications/Thunderbird.app --args -no-remote -P "notthedefaultprofile"

I'm not sure what the --args option is for, but may be this is Mac specific.

Is it possible to have two separate installations each with their own unique profiles ...

I'm not exactly sure what you're trying to achieve here. You could use two separate OS accounts, but may be this isn't what you want.

Sometimes clicking when when clicking on an out-of-browser link, there seems to be a mix-up of profiles and consequently sometimes corrupts the old firefox profile

That is indeed somewhat problematic, and should be avoided. As of Firefox 67 there's a new feature called 'Dedicated profiles per Firefox installation'. https://support.mozilla.org/kb/dedicated-profiles-firefox-installation

This may actually fix your problem with Firefox. Whether this will be included in the upcoming Thunderbird 68 release, I don't know.

Thank you again for your quick response christ1!

It's good that you're aware of some problematic issues that can potentially arise when using the no-remote method.

Is it possible to have two separate installations each with their own unique profiles ...

I'm not exactly sure what you're trying to achieve here. You could use two separate OS accounts, but may be this isn't what you want.

Same OS account, two completely different installations just like installing Firefox and Firefox Developer Edition - I can open either at a click of a button without worrying about profiles etc. I hope you're now a bit more clear on what I'm trying to achieve.

It might all boil down to this: Can I just edit/modify an installation file so that I can install Thunderbird as a different edition? If yes, what are the steps for this? I've had a quick look at the build page: https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Simple_Thunderbird_build

Although the link says "simple Thunderbird build" my quick look tells me it's not that simple. I would think it's best not build a new Thunderbird when I just need something almost identical to a regular build.

Same OS account, two completely different installations just like installing Firefox and Firefox Developer Edition - I can open either at a click of a button without worrying about profiles etc.

As said before, for Firefox check the 'Dedicated profiles' feature which shipped with FF67. For any more information you may ask in the Firefox forum.

Whether TB68 ships with that remains to be seen.